Maybe it's just me, but I can't imagine getting any meaningful amount of rain water from under the pop top seal. Seems like the least likely place I can think of, if you ask me.
Atrometer, you mentioned "driving" rain. There is a HUGE gap at the forward end of the poptop, between it and and the sliding hatch. You could practically pass your hand through it. When trailering in heavy rain, we get a ton of water through there, so much that I'll stuff a towel in the gap if I think about it in time. But then again, that's at 60 mph, which would be one helluva driving rain while the boat was sitting still.
But yeah, JMHO and all, I could be wrong, but the poptop seal just seems like a really long shot to me. Companionway boards are much more likely to leak, followed by windows, chainplates, and just about every other deck penetration. Man my '79 C22 practically RAINED water inside when I first bought her.